ZONE ISOLATION CONTROL SYSTEM FOR TRANSPORT REFRIGERATION UNIT

Abstract

Multi-zone transport refrigeration units (TRUs). A combination of temperature controlled flow of cold air and time controlled refrigerant distribution is used to improve cooling performance and reduce power consumption. This dual-control zone isolation system makes it possible to use solar panels to power the TRU.

Claims

1. A high efficiency battery powered TRU with zone isolation comprising of: A. a refrigeration system wherein timer controls are used to limit refrigerant flow from a freezer zone to remote evaporators, said remote evaporators being located in refrigeration zones other than a host freezer zone; B. a refrigeration air handling system wherein air is extracted directly from a post evaporator cold-air chamber of said host freezer zone, said extracted air being distributed to each said refrigeration zone to control a single zone temperature, or multiple temperatures in multiple zones, by airflow control using a combination of fans, ducts, gates and air temperature controllers.

2. The high efficiency battery powered TRU with zone isolation as claimed in claim 1 wherein, in addition, there is a battery that powers said TRU refrigeration system that consumes less than 18 Kwh of electrical energy.

3. A high efficiency battery powered TRU as claimed in claim 2 wherein, in addition, said zone isolation consists of a knock sensor detector for liquid refrigerant returning to a compressor that: i. switches on a return line heater keeping the returning refrigerant in gas phase, and ii. alternatively shuts off said refrigeration system.

4. A high efficiency battery powered TRU as claimed in claim 2 that, in addition, includes a sensor that detects a refrigerator door open condition and sends a signal to said zone isolation controller to completely shut down said refrigerator or reduce its cooling duty cycle.

5. A high efficiency battery powered TRU as claimed in claim 2 wherein, in addition, there is a compressor driven by a motor selected from the group consisting of: i. A direct current brushed motor; ii. direct current brushless motor, iii. an induction alternative current motor with a direct current to alternate current converter.

6. A high efficiency battery powered TRU as claimed in claim 5 wherein the motor is a separate component from the compressor or integral with the compressor.

7. A high efficiency battery powered TRU as claimed in claim 1 wherein, in addition, wherein said refrigeration air handling system is conducted wherein return air is directed through one side of said evaporator and then its direction is reversed to make said air pass through an opposite side of said evaporator.

8. A high efficiency battery powered TRU as claimed in claim 1 wherein there is, in addition, a thermoelectric device used as a sub-cooler to add capacity to a condenser and separately used to provide cooling for said temperature sensors.

9. A high efficiency battery powered TRO as claimed in claim 2 wherein a solar panel is used to charge said battery and run said TRU refrigeration system.

10. A high efficiency battery powered TRU as claimed in claim 1 wherein said solar panel is the only power generation source and said power generated is sufficient to supply all the power necessary to run said refrigeration unit.

11. A high efficiency battery powered TRU as claimed in claim 1 wherein there is, in addition, a backup wheel generator system that only makes power during deceleration.

12. A high efficiency battery powered TRU as claimed in claim 11 wherein said high efficiency battery powered TRU is programed to continuously produce power during emergency low-battery voltage situations.

13. An electric power generation plant comprising a fleet of high efficiency battery powered TRUs as claimed in claim 1 that are equipped with solar panels, ganged together in a charging network.

14. A high efficiency battery powered TRU as claimed in claim 1 wherein airflow ducts are recessed into the ceiling of said refrigeration chamber.

15. A high efficiency battery powered TRU as claimed in claim 1 wherein cold plates composed of eutectic solutions or phase change materials are sued to cool refrigeration chambers and battery assemblies.

16. A high efficiency battery powered TRU as claimed in claim 1 wherein a box containing a battery assembly is filled with expanded glass beads,

17. A high efficiency battery powered TRU as claimed in claim 1 wherein a box containing a battery assembly is manufactured from expanded glass aggregate panels.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0028] FIG. 1 is a full side view in perspective of a reefer showing predetermined zones and the use of a solar panel on the top of the semi-trailer. A wheel driven generator assembly and battery are shown.

[0029] FIG. 2 is a schematic showing timer controlled relay switches providing electric power on and off to each cooling zone individually.

[0030] FIG. 3 shows cold air being routed from the freezer to the refrigerator using a system of fans, ducting and controlled gates as well as an electric heating element in the evaporator area that is used to provide refrigerator heating in cold ambient conditions and a rod heater to defrost the evaporator.

[0031] FIG. 4 is art enlarged view of the refrigeration unit showing the knock sensor on the compressor and the return refrigerant line heater. The DC to AC inverter and AC motor are shown.

[0032] FIG. 5 is full rear view of the TRU showing the partially open rolling door and switch.

[0033] FIG. 6 is a view in perspective, from the top, of the U-shaped airflow through the double-pass evaporator.

[0034] FIG. 7 is a full front view of a cold plate array composed of a eutectic solution or phase change material.

[0035] FIG. 8 is a view in perspective, from the side, of a thermoelectric cold plate sub-cooler.

[0036] FIG. 9 is an end view of airflow ducting recessed into the ceiling of a refrigeration chamber.

DETAILED DESCRIPTION OF THE INVENTION

[0037] A typical TRU layout of the instant invention is shown in FIG. 1 where zone one (Z1) is a freezer, zone two (Z2) a refrigerator and zone three (Z3) may be a second refrigerator or an ambient temperature chamber for dry goods.

[0038] The freezer (Z1) requires the most refrigerant to hold sub-freezing temperature. Present art TRU's take refrigerant from the Z1 evaporator and move it to the Z2 and Z3 evaporators whenever Z2 or Z3 demand cooling based on temperature. Z2 and Z3 take priority over Z1 and Z1 performance suffers putting frozen product at risk. This instant invention uses a timer priority system so each zone is duty cycled such that Z1 has priority and the critical freezer temperature is strictly maintained. Z1 temperature control is improved and overall power consumption is reduced.

[0039] Timer relay switches (2) provide electric power on and off to each cooling zone individually as illustrated in FIG. 2. The duty cycle of each zone is set according to the cooling requirements of that particular zone. This zone isolation allows cooling to be prioritized for the freezer, while maintaining some refrigerator cooling. If the refrigerator requires more cooling because of the lack of refrigerant, cold air from the freezer is used to supplement the refrigerator cooling.

[0040] Cold air is routed from the freezer to the refrigerator using the system of fans (3), ducting (4) and controlled gates (5) as illustrated in FIG. 3. This means of cooling the refrigerated areas is faster acting and more efficient then moving refrigerant to the evaporators in the refrigerator.

[0041] Also shown in FIG. 3, is an electric heating element (6) in the evaporator area that is used to provide refrigerator heating in cold ambient conditions. It is also used to defrost the evaporator. This electric defrost adds to the efficiency of the all-electric battery powered TRU. The electric defrost is more efficient and faster acting than current defrost systems that use hot refrigerant gas.

[0042] A thermo-electric cooling plate (7) is used after the main condenser as a sub-condenser to remove additional heat from the refrigerant. This electric condenser increases the overall capacity of the refrigeration system. The hot refrigerant (8) is channeled through a machined block (9) attached to the cooling plate of the thermo-electric cooler and heat is transferred from the refrigerant to the outside ambient air as shown in FIG. 8.

[0043] The timer controlled refrigerant priority assembly, temperature controlled cold-air flow assembly (FIG. 3) and thermo-electric sub-condenser can be used to improve any TRU. They are especially beneficial however to the battery-powered all electric TRU shown in FIG. 1. The dual-control zone isolation system of the instant invention brings the power consumption of a 30,000 BTU/hour battery-powered TRU from 6,000 watts down to 3,000 watts. This makes it possible for the first time to use solar panels (1) as the sole power source for mobile refrigeration systems such as a TRU.

[0044] Semi-trailers have upwards of 400 square feet of roof area available. Current solar panel efficiency will produce 2,000 watts or more of solar-electrical power from this area. Storing ten hours of solar panel produced power in the battery of the battery-powered TRU provides 20 Kwh of electrical energy, enough to run the battery-powered TRU on a typical delivery route. The battery/solar-powered TRU has zero emissions during operation.